Direct Acylation of Unactivated Alkyl Halides with Aldehydes through N-Heterocyclic Carbene Organocatalysis.

Catalytic acylation of organohalides with aldehydes is an ideal strategy for the direct synthesis of ketones. However, the utilization of unactivated alkyl halides in such a transformation remains a formidable challenge. In this study, we developed a cross-coupling reaction of aldehydes with unactivated alkyl halides through N-heterocyclic carbene catalysis. With this protocol, various ketones could be rapidly synthesized from readily available starting materials under mild conditions. This organocatalytic system was successfully applied in the late-stage functionalization of pharmaceutical derivatives. Mechanistic investigations suggest a closed-shell nucleophilic substitution mechanism for this reaction.

Indium Tin Oxide Thin-Film Thermocouple Probe Based on Sapphire Microrod.

Indium tin oxide (ITO) thin-film thermocouples monitor the temperature of hot section components in gas turbines. As an in situ measuring technology, the main challenge of a thin-film thermocouple is its installation on complex geometric surfaces. In this study, an ITO thin-film thermocouple probe based on a sapphire microrod was used to access narrow areas. The performance of the probe, i.e., the thermoelectricity and stability, was analyzed. This novel sensor resolves the installation difficulties of thin-film devices.

Carbetocin vs oxytocin for prevention of postpartum hemorrhage after vaginal delivery: A meta-analysis.

OBJECTIVE: To evaluate the efficacy and safety of carbetocin for prevention of postpartum hemorrhage in women undergoing vaginal delivery compared with oxytocin. METHODS: We conducted a systemic literature search in PubMed, the Cochrane Library, and Embase without language restrictions from inception of each of database to November 18th, 2018. Randomized controlled trials with outcome measure of blood loss ≥500 ml were eligible if they compared carbetocin with oxytocin to prevent postpartum hemorrhage during the third stage of labor in women undergoing vaginal delivery. RESULTS: This meta-analysis of 5 randomized controlled trials (30,314 women) indicated that there was no significant difference between carbetocin and oxytocin in blood loss ≥500 ml in women undergoing vaginal delivery (relative risks (RRs), 0.52; 95% confidence intervals (CIs), 0.24 to 1.15; P = .11; I = 69%). Sensitivity analyses showed the same results. No significant differences were found in blood loss ≥1000 ml, use of additional uterotonic agents, blood transfusion, uterine massage, flushing, vomiting, abdominal pain, nausea, dizziness, headache, palpitation, itching, and shivering. CONCLUSIONS: This meta-analysis showed that carbetocin was as effective and safe as oxytocin for prevention of postpartum hemorrhage in women undergoing vaginal delivery, and the choice of carbetocin for routine prophylaxis will depend on cost-effectiveness.

A Through-Hole Lead Connection Method for Thin-Film Thermocouples on Turbine Blades.

To solve the current problems with thin-film thermocouple signals on turbine blades in ultra-high temperature environments, this study explores the use of a through-hole lead connection technology for high-temperature resistant nickel alloys. The technique includes through-hole processing, insulation layer preparation, and filling and fixing of a high-temperature resistant conductive paste. The through-hole lead connection preparation process was optimized by investigating the influence of the inner diameter of the through-hole, solder volume, and temperature treatment on the contact strength and surface roughness of the thin-film for contact resistance. Finally, the technology was combined with a thin-film thermocouple to perform multiple thermal cycling experiments on the surface of the turbine blade at a temperature of 1000 °C. The results show that the through-hole lead connection technology can achieve a stable output of the thin-film thermocouple signal on the turbine blade.

Cervical Pessary for Prevention of Preterm Birth: A Meta-Analysis.

To investigate the efficacy of cervical pessary placement in preventing preterm birth and perinatal morbidity and mortality in asymptomatic women with a singleton pregnancy and a short cervix, we searched literature in relevant databases. The meta-analysis of the 3 included trials (1412 women) showed cervical pessary placement did not reduce the risk of spontaneous preterm birth <34 weeks in these women (risk ratio (RR), 0.71; 95% confidence interval (CI), 0.21-2.43, P = 0.59; I2 = 90%). The sensitivity analyses by excluding one trial at one time showed the same results. This meta-analysis also showed that cervical pessary did not prevent preterm birth <34, 30, 28 weeks and was not associated with respiratory distress syndrome, necrotising enterocolitis, intraventricular haemorrhage, neonatal sepsis, retinopathy of prematurity, fetal death, neonatal death, perinatal death, birth weight <1500 g, birth weight <2500 g, premature preterm rupture of membranes, corticosteroid treatment for fetal maturation, and admission to neonatal intensive care unit. Although this meta-analysis showed cervical pessary placement did not reduce the risk of preterm birth in women with a singleton pregnancy and a short cervix, we could not confirm or refute this conclusion, and large-scale randomised controlled trials are urgently needed.